Supported lewis acid catalysts for hydrocarbon conversion reactions

ABSTRACT

A supported Lewis acid catalyst system for catalyzing hydrocarbon conversion reactions including cationic polymerization, alkylation, isomerization and cracking reactions is disclosed, wherein the catalyst system comprises an inorganic oxide support having immobilized thereon at least one relatively strong Lewis acid and at least one relatively weak Lewis acid.

This is a divisional of application Ser. No. 08/221,202, filed Mar. 31,1994, now U.S. Pat. No. 5,561,095.

TECHNICAL FIELD

This invention relates to supported Lewis acid catalyst systems, toprocesses for preparing the catalyst systems, and to various hydrocarbonconversion reactions which are performed in the presence of suchcatalyst systems. More particularly, the invention relates to effectivecatalyst systems for cationic polymerization, alkylation, isomerizationand hydrocarbon cracking reactions comprising at least two Lewis acidsimmobilized on an inorganic substrate containing surface hydroxylgroups, wherein at least one of the Lewis acids is a relatively strongLewis acid and at least one of the Lewis acids is a relatively weakLewis acid.

BACKGROUND OF THE INVENTION

Lewis acids are among the most powerful initiators for hydrocarbonconversion reactions. Such catalysts have been used in liquid, gaseousand solid form, and have been supported or immobilized on variouspolymeric and inorganic substrates, including, for example, silica gel,alumina, graphite and various clays.

Both supported and unsupported Lewis acid catalysts have been used withvarying degrees of success for initiating alkylation reactions and thecarbocationic polymerization of olefins, such as isobutene. However, inspite of the advances made in the fields of alkylation andpolymerization catalysis, there continues to be interest in developinghighly efficient catalyst systems which can be recycled or reused inhydrocarbon conversion processes. The present invention was developedpursuant to this interest.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided an immobilized Lewis acid catalyst system which is free fromany added titanium-, vanadium-, hafnium- and zirconium-containing Lewisacids and which is active for various hydrocarbon conversion reactions,including, in particular, carbocationic olefin polymerizations andalkylation reactions. According to this aspect, the immobilized catalystsystem is in the form of a particulate inorganic substrate on whichthere is supported or immobilized at least two separate Lewis acids,wherein at least one of the Lewis acids comprises a strong Lewis acid,such as an alkyl aluminum, an alkyl aluminum halide, an aluminum halideor a boron halide, and wherein at least one of the Lewis acids comprisesa weak Lewis acid, such as a magnesium halide, an alkyl magnesiumhalide, an iron halide, a tin halide or aralkyl zinc. The particulateinorganic substrate which is to be used as the catalyst support maycomprise any conventional inorganic substrate having surface hydroxylgroups, i.e., --OH groups. Such substrates include, for example, powderscomprised of or including silica, alumina, magnesia, titania, zeolites,silica-alumina, silica-titania, silica-magnesia or the like.

In another aspect, an immobilized Lewis acid catalyst system may beprepared by reacting an inorganic, silicon-containing substrate havingsurface silanol groups, i.e., Si--OH groups, with both a relativelystrong Lewis acid and a relatively weak Lewis acid, such that a firstportion of the silanol groups on the substrate are converted to Si--O--Mgroups, where M is a metal ion derived from the relatively strong Lewisacid, and such that a second portion of the silanol groups are convertedto Si--O--M', where M' is a metal ion derived from the relatively weakLewis acid. In this aspect, it is not critical whether the inorganicsubstrate is first contacted with the strong Lewis acid or with the weakLewis acid. Also in connection with this aspect, depending upon theidentity of the strong and weak Lewis acids that are utilized, it may bedesirable to contact the catalyst system with a halogenating agent, suchas an alkyl chloride, hydrogen chloride, chlorine or the like, in orderto control its acidity.

Another aspect of the present invention provides a process for using theabove immobilized Lewis acid catalyst system, which is free from anyadded titanium-, vanadium-, hafnium- and zirconium-containing Lewisacids, for polymerizing a variety of monomers into homopolymers andcopolymers, e.g., polyalkenes, by contacting the monomers with theimmobilized Lewis acid catalyst system of this invention undercarbocationic polymerization conditions. The monomers which may be usedaccording to this aspect of the invention include those havingunsaturation which are conventionally polymerizable using carbocationicLewis acid catalyst polymerization techniques, such as, for example,olefins characterized by the presence in their structure of the group>C═CH₂. The catalyst system in this aspect is preferably free from anyadded titanium-, vanadium-, hafnium- and zirconium-containing Lewisacids which am known to catalyze Ziegler-type polymerization reactionsand to produce primarily stereoregular polymers, as opposed to thegenerally amorphous polymers which are produced in accordance with thecationic polymerization process contemplated herein. To effect thepresent cationic polymerization process, in a preferred process, atleast one inlet stream comprising monomer feed to be polymerized is fedto a reactor having at least one discharge stream. The monomer stream ispolymerized in the reactor in the presence of the above-describedimmobilized Lewis acid catalyst system. The resulting polymerizedpolymer is removed from the reactor along with the unreacted monomers inthe discharge stream while the immobilized catalyst system is retainedin the reactor.

Yet another aspect of the invention is the preparation of a uniqueolefin polymer product which is characterized by having a high degree ofreactive vinylidene unsaturation. In this aspect, it has been found, forexample, that at least 40% of the polymer chains of polyisobutylenewhich has been prepared by cationic polymerization in the presence ofthe above-described Lewis acid catalyst systems exhibit terminal ornon-terminal vinylidene unsaturation. In contradistinction, typicallyless than about 20% of the polymer chains of polyisobutylene preparedusing a conventional non-supported strong Lewis acid catalyst, e.g.,ethyl aluminum dichloride Lewis acid catalyst, will contain terminal ornon-terminal vinylidene unsaturation.

In still other aspects, the catalyst systems of this invention may beused in hydrocarbon conversion processes such as isomerization, crackingand alkylation. As is known in the art, alkylation may be simplydescribed as the addition or insertion of an alkyl group into asubstrate molecule. Of particular interest is the alkylation of aromaticand hydroxy aromatic substrates, such as benzene, toluene, xylene andphenol. Suitable alkylating agents include, for example, olefins,alkanes, alkyl halides and mixtures. However, particularly preferredalkylating agents for use in the present invention include olefins,including olefin oligomers, such as propylene oligomers, having fromabout 6 to about 50 carbon atoms and having one double bond permolecule.

A significant advantage of the present catalyst systems is that they arestable and do not leach or otherwise deposit free Lewis acid into thereaction medium or, more importantly, into the reaction products.Another advantage is that the present catalyst systems are usable formultiple reaction cycles (in the context of a batch process) withoutregeneration, resulting in substantial cost savings, as well as theelimination of significant amounts of hazardous waste typicallygenerated in conventional Lewis acid processes. Not only can thesupported Lewis acid catalyst systems of the present invention beemployed in multiple batch reaction cycles or on a continuous basis, butthey can also be recovered readily during hydrocarbon conversionprocesses such as polymerization, alkylation, isomerization andalkylation by simple filtration techniques.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The novel immobilized Lewis acid catalyst systems of the presentinvention may be prepared by fixing or immobilizing at least two Lewisacids on the surface of an inorganic substrate which contains surface--OH groups, wherein at least one of the Lewis acids is a relativelystrong Lewis acid and at least one of the Lewis acids is a relativelyweak Lewis acid. Generally, the metal of each Lewis acid will differ.

For the purposes of this invention the terms fixed or immobilized areused interchangeably and are defined as wherein substantially all of theactive two Lewis acids are chemically bound to the substrate, e.g., byforming --O-metal bonds with the metals of the Lewis acids. In otherwords, the Lewis acids are not readily extracted by a solvent or diluentunder conditions of polymerization, alkylation, isomerization orcracking.

The acid strength of a Lewis acid is dependent both upon the metal atomin the Lewis acid and upon the electronic effect of the ligand that isassociated with the metal atom, and can be measured by reacting theLewis acid with a base, typically a ketone or nitrile, and the observingby infra-red spectroscopy the shift of the characteristic absorption vC═O or v C N. The weaker Lewis acids give a low absortpion shift,whereas the stronger Lewis acids give a higher shift. See, for example,W. Kuran et al., Makromol. Chem., 154, pp. 71-79 (1972), which discussesthe relative strengths of Lewis acids in the context of metal halide andorganometal halide catalyzed copolymerization and cyclodimerization ofacrylonitrile and butadiene.

As a general rule, for the purposes of this specification and claims,the acid strength of a Lewis acid having a halogen ligand and a givenmetal central atom, such as AlCl₃ or C₂ H₅ AlCl₂, increases with thenumber of halogen atoms. Thus, the relative strength of aluminum andhalogen-containing Lewis acids increases as follows:

    AlCl.sub.3 stronger than (>) C.sub.2 H.sub.5 AlCl.sub.2 >(C.sub.2 H.sub.5).sub.2 AlCl>(C.sub.2 H.sub.5).sub.3 Al

Another general rule for the purposes of this invention is that thestrength of a halide-containing Lewis acid of a given halide ligand,such as a chloride, increases in strength as follows:

    BCl.sub.3 stronger than (>) AlCl.sub.3 >SnCl.sub.4 >MgCl.sub.2

Also, whatever the ligand, the magnesium-containing Lewis acids areweaker strength Lewis acids that are the aluminum-containing Lewisacids.

Thus, among the relatively strong Lewis acids which are contemplated foruse in this invention, there may be included the halides, alkyl halidesand alkyl compounds of aluminum, the halides of boron, and equivalentsthereof. Preferred strong Lewis acids include, for example, aluminumcompounds having the formula R_(n) AlX_(3-n), where R is a monovalenthydrocarbon radical, preferably C₁ -C₁₂ alkyl or aryl, n is a numberfrom 0 to 3, and X is a halogen independently selected from the groupconsisting of fluorine, chlorine, bromine and iodine. Non-limitingexamples of such preferred strong Lewis acids include triethyl aluminum((C₂ H₅)₃ Al), diethyl aluminum chloride ((C₂ H₅)₂ AlCl), ethyl aluminumdichloride (C₂ H₅ AlCl₂), ethyl aluminum sesquichloride ((C₂ H₅)₁.5AlCl₁.5), aluminum chloride (AlCl₃) and mixtures thereof.

Among the relatively weak Lewis acids contemplated for use in thisinvention are the halides, alkyl halides and alkyl compounds ofmagnesium, iron, tin, zinc and equivalents thereof, including, forexample, magnesium compounds having the formula R¹ _(m) MgX¹ _(2-m),where R¹ is a monovalent hydrocarbon radical, preferably C₁ -C₁₂ alkylor aryl, m is 1 or 2, and X¹ is a halogen independently selected fromthe group consisting of fluorine, chlorine, bromine and iodine.Non-limiting examples of such preferred weak Lewis acids include dibutylmagnesium ((C₄ H₉)₂ Mg), butyl magnesium chloride (C₄ H₉ MgCl), SnCl₄and mixtures thereof.

The concentration of total Lewis acid (strong plus weak) present on thesubstrate will range from about 0.5 to about 20% by weight, based ontotal weight of the metal or metals of the Lewis acids; preferably fromabout 1 to about 10%; most preferably from about 2 to about 8%; forexample, about 5 weight % of total Lewis acid metal on the substrate.The molar ratio of strong Lewis acid to weak Lewis acid is generally inthe range of from about 100:1 to about 1:100; preferably from about 50:1to about 1:50; most preferably from about 10:1 to about 1:10.

As indicated above, titanium-, vanadium-, hafnium-, andzirconium-containing Lewis acids, such as TiCl₃, VCl₄, and HfCl₄ andZrCl₄ should be avoided inasmuch as they promote Ziegler-type catalysis.

The substrates to which the strong and weak Lewis acids may be fixedinclude any of the conventional inorganic oxide substrates which containfree hydroxyl groups which can react with the selected Lewis acids.Generally speaking any metal oxide which has surface hydroxyl groups canbe utilized as the substrate. The terms "metal oxide" and "inorganicoxide", although typically used herein in the singular, are meant toinclude single oxides, such as silica or alumina, as well plural andcomplex oxides, such as silica-alumina, silica-alumina-thoria, zeolitesand clays.

Non-limiting examples of such inorganic oxides include silica, alumina,titania, magnesia, silica-alumina, silica-titania, silica-magnesia,silica-alumina-thoria, silica-alumina-zirconia, crystallinealuminosilicates, including synthetic zeolites such as, for example, A,X, and ZSM-5 zeolites, and naturally occurring zeolites such as, forexample, faujasite and mordenite, and open lattice clays, such asbentonite and montmorillonite. The preferred inorganic oxide substratestypically are in the form of powders or particles, and include a majorcomponent of silica or alumina or a mixture of both.

Particularly suitable as substrates are those solid inorganic oxidecompositions known as metal oxide gels or gel oxides. Preferred oxidegel materials include those gel materials selected from the groupconsisting of silica, alumina, alumina-silica, zeolites and open latticeclays. Silica gel and silica-alumina gel substrates are particularlypreferred.

The particular substrate materials are not critical, provided that theydo not interfere with the conversion processes for which the resultingimmobilized Lewis acid catalyst systems are intended to be used, andprovided that they contain the hydroxyl groups which are necessary toreact with, and thereby fix or immobilize, the Lewis acid catalystmaterials.

The Lewis acids may be immobilized on the inorganic substrate bycontacting the substrate with the selected Lewis acids at a temperatureranging from room temperature to elevated temperatures on the order ofabout 150° to 200° C. or higher, and preferably, from about roomtemperature to about 110° C. The substrate may be contacted first withthe strong Lewis acid and then with the weak Lewis acid. Alternatively,the substrate may be contacted first with the weak Lewis acid, and thenwith the strong Lewis acid. Also, the substrate may be contactedsimultaneously with both the strong and the weak Lewis acids. Also,depending upon the acidity of the substrate after having been contactedwith the strong and weak Lewis acids, it may be desirable to furthercontact the substrate with a halogenating agent to convert residualhydrocarbyl radicals to halogen moieties. In this latter instance, thehalogenating agents which may be employed include, for example, alkylhalides, halogens, hydrogen halides. Non-limiting examples of suitablehalogenating agents include HCl, Cl₂ and compounds having the formula R²Cl, where R² is a hydrocarbon radical, typically a C₂ -C₁₀, preferably aC₂ -C₅, secondary or tertiary alkyl radical, e.g., t-butyl chloride.

Immobilization of the strong and weak Lewis acids in accordance withpreferred aspects of the present invention may be illustrated by thefollowing schematic reaction sequencs: ##STR1##

The novel immobilized catalysts of the present invention can be used topolymerize a variety of monomers into homopolymers and copolymers, e.g.,polyalkenes. The monomers include those having unsaturation which areconventionally polymerizable using carbocationic Lewis acid catalystpolymerization techniques, and monomers which are the equivalentsthereof. The terms cationic and carbocationic are used interchangeablyherein. Olefin monomers useful in the practice of the present inventionare polymerizable olefin monomers characterized by the presence of oneor more ethylenically unsaturated groups. The monomers can be straightor branched monoolefinic monomers, such as vinyl ethers, propylene,1-butene, isobutylene, and 1-octene, or cyclic or acyclic conjugated ornon-conjugated dienes.

Suitable olefin monomers are preferably polymerizable terminal olefins;that is, olefins characterized by the presence in their structure of thegroup >C═CH₂. However, polymerizable internal olefin monomers (sometimesreferred to in the patent literature as medial olefins) characterized bythe presence within their structure of the group ##STR2## can also beused to form polymer products. When internal olefin monomers areemployed, they normally will be employed with terminal olefins toproduce polyalkenes which are interpolymers. For purposes of theinvention, when a particular polymerized olefin monomer can beclassified as both a terminal olefin and an internal olefin, it will bedeemed to be a terminal olefin. Thus, 1,3-pentadiene (i.e., piperylene)is deemed to be a terminal olefin for purposes of this invention.

Preferred monomers used in the method for forming a polymer inaccordance with the present invention are preferably selected from thegroup consisting of alpha-olefins and typically C₃ -C₂₅ alpha olefins.Suitable alpha-olefins may be branched or straight chain, cyclic, andaromatic substituted or unsubstituted, and are preferably C₃ -C₁₆alpha-olefins. Mixed olefins can be used (e.g., mixed butenes).

The alpha-olefins, when substituted, may be directly aromaticsubstituted on the 2-carbon position (e.g., monomers such as CH₂ ═CH--C₆H₅ may be employed). Representative of such monomers include styrene,and derivatives such as alpha-methyl styrene, para-methyl styrene, vinyltoluene and its isomers.

In addition, substituted alpha-olefins include compounds of the formulaH₂ C═CH--R³ --X² wherein R³ represents C₁ to C₂₂ alkyl, preferably C₁ toC₁₀ alkyl, and X² represents a substituent on R³ and can be aryl,alkaryl, or cycloalkyl. Exemplary of such X² substituents are aryl of 6to 10 carbon atoms (e.g., phenyl, naphthyl and the like), cycloalkyl of3 to 12 carbon atoms (e.g., cyclopropyl, cyclobutyl, cyclohexyl,cyclooctyl, cyclodecyl, cyclododecyl, and the like) and alkaryl of 7 to15 carbon atoms (e.g., tolyl, xylyl, ethylphenyl, diethylphenyl,ethylnaphthyl, and the like). Also useful are bicyclic, substituted orunsubstituted olefins, such as indene and derivatives, and bridgedalpha-olefins of which C₁ -C₉ alkyl substituted norbornenes arepreferred (e.g., 5-methyl-2-norbornene, 5-ethyl-2-norbornene,5-(2'-ethylhexyl)-2-norbornene, and the like).

Illustrative non-limiting examples of preferred alpha-olefins arepropylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, and1-dodecene.

Dienes suitable for purposes of this invention include straight chain,hydrocarbon diolefins or cycloalkenyl-substituted alkenes having about 6to about 15 carbon atoms, including, for example, 1,4-hexadiene,5-methyl-1,4-hexadiene, 1,3-cyclopentadiene, tetrahydroindene,dicyclopentadiene, 5-methylene-2-norbornene,5-cyclohexylidene-2-norbornene, 5-vinyl-2-norbornene, allyl cyclohexeneand vinyl cyclododecene.

Of the non-conjugated dienes typically used, the preferred dienes aredicylcopentadiene, methyl cyclopentadiene dimer, 1,4-hexadiene,5-methylene-2-norbornene, and 5-ethylidene-2-norbornene. Particularlypreferred diolefins are 5-ethylidene-2-norbornene and 1,4-hexadiene.

The polymers and copolymers which can be manufactured by the process ofthe present invention are those which can be manufactured by acarbocationic polymerization process and include but are not limited topolyalkenes, such as polyisobutene, poly(1-butene), polystyrene,isobutene styrene copolymers, and the like. The term copolymer as usedherein is defined to mean a polymer comprising at least two differentmonomer units.

In particular, the immobilized catalysts of the present invention areespecially useful for manufacturing polyisobutene and poly(1-butene)from feedstreams containing butene monomers. It is especially preferredto use refinery feed streams containing C₄ monomers, commonly referredto as Raffinate I and Raffinate II.

The polymers and copolymers which are manufactured using the immobilizedLewis acid catalyst system of the present invention may be referred toas reactive polymers in the sense that they are characterized by havingterminal or non-terminal vinylidene unsaturation in at least 40% oftheir polymer chains. Substantial non-terminal vinylidene unsaturationin conventional Lewis acid catalyzed polymers has not been observed.This differs from polymer products which have been prepared usingconventional non-supported Lewis acid catalysts wherein a single Lewisacid, such as ethyl aluminum dichloride, is employed (typically lessthan 20% of the chains of polymers of this type contain vinylideneunsaturation), as well as from polymer products prepared usingconventional BF₃ catalysis (typically 40% or more of the polymer chainscontain terminal vinylidene).

For purposes of this comparison, polyisobutylene polymer chains havingterminal vinylidene unsaturation may be illustrated as follows: ##STR3##

Polyisobutylene polymer chains having non-terminal (internal) vinylideneunsaturation may be illustrated as follows: ##STR4##

The carbocationic polymerization process of the present invention may becarried out in a polar or, preferably, non-polar reaction medium as acontinuous, semi-continuous or batch process. Suitable polar solventswhich may be used as the polymerization reaction medium include, forexample, methyl chloride, dichloromethane, ethyl chloride ornitromethane or the like, whereas suitable non-polar solvents include,for example, carbon tetrachloride, hexane, heptane, cyclohexane, andmore generally the linear or branched, saturated or unsaturatedhydrocarbon solvents which can be found in the stream of monomersobtained from various cracking processes.

The reactors which may be utilized in the practice of the presentinvention include conventional reactors and equivalents thereof such asbatch reactors, stirred tank reactors, fluidized bed reactors, andcontinuous tank or tubular reactors and the like.

The reactor will contain sufficient amounts of the immobilized catalystsystem of the present invention effective to catalyze the polymerizationof the monomer containing feedstream such that a sufficient amount ofpolymer having desired characteristics is produced. The reactionconditions will be such that sufficient temperature, pressure andresidence time are maintained effective to maintain the reaction mediumin the liquid state and to produce the desired polymers having thedesired characteristics.

Typically, the catalyst to monomer ratio utilized will be thoseconventional in this art for carbocationic polymerization processes. Forexample, catalyst to monomer mole ratios will typically be about 1/15000to about 1/50, more typically about 1/5000 to about 1/100, andpreferably about 1/1000 to about 1/200. This mole ratio will becalculated by determining the number of Lewis acid catalyst sites in theimmobilized Lewis acid catalyst. This can be done by using conventionalanalytic testing techniques such as elemental analysis, NMR (e.g.,aluminum NMR) and absorption spectroscopy. Once the number of Lewis acidsites per unit of immobilized catalyst is known, the mole ratio iscalculated in a conventional manner.

The polymerization reaction temperature is conveniently selected basedon the target polymer molecular weight and the monomer to be polymerizedas well as standard process variable and economic considerations, e.g.,rate, temperature control, etc. Typically temperatures from about -100°C. to about +75° C. are useful in the process; more typically about -50°C. to about +50° C., depending, as noted above, on polymer molecularweight. Reaction pressure will typically be about 200 kPA to about 1600kPA, more typically about 300 to about 1200 kPA, and preferably about400 to about 1000.

The monomer feedstream to this process may be at least one pure or mixedmonomer feedstream or combinations thereof. Preferably, the monomerfeedstream may be mixed with solvents such as hexane or heptane, and thelike. A preferred feedstock to this process may be a pure or mixedrefinery butene stream containing one or more of 1-butene, 2-butene,(cis and trans), and isobutene. The preferred feedstocks (preferred onan availability and economic basis) are available from refinerycatalytic crackers and steam crackers. These processes are known in theart. The butene streams typically contain between about 6 wt. % to about50 wt. % isobutylene together with 1-butene, cis- and trans-2-butene,isobutane and less than about 1 wt. % butadiene. One particularlypreferred C₄ feedstream is derived from refinery catalytic or steamcracking processes and contains about 6-45 wt. % isobutylene, about25-35 wt. % saturated butanes and about 15-50 wt. % 1- and 2-butenes.Another preferred C₄ feedstream is referred to as Raffinate IIcharacterized by less than about 6 wt. % isobutylene.

The monomer feedstream is preferably substantially anhydrous, that is,it contains less than 50 ppm, and more preferably less than about 30ppm, and most preferably less than about 10 ppm, by weight of water.Such low levels of water can be obtained by contacting the feedstream,prior to the reactor, with a water absorbent (such as NaH, CaCl₂, CaSO₄,molecular sieves and the like) or by the use of distillation drying.

The monomer feedstream is typically substantially free of any impuritywhich is adversely reactive with the catalyst under the polymerizationconditions. For example, the monomer feed preferably should besubstantially free of bases (such as caustic), sulfur-containingcompounds (such as H₂ S, COS, and organo-mercaptans, e.g., methylmercaptan, ethyl mercaptan), N-containing compounds, and the like.

The monomer feedstream is typically substantially free of aromaticcompounds to avoid alkylation reactions. Therefore, use of an aromaticsolvent generally is not envisioned in this polymerization process.

A material acting as a cocatalyst (or promoter) may optionally be addedto a monomer feedstock before that feed is introduced to a reactor or itmay be added separately to the reactor, e.g., to the catalyst bed. Avariety of conventional cocatalysts or equivalents can be used includinginorganic acids such as hydrogen halides, lower alcohols, C₂ -C₂₄secondary or tertiary alkyl halides, organic acids such as carboxylicacids and sulfonic acids, and the like. For example, gaseous, anhydrousHCl, may be employed as a cocatalyst. The HCl will be employed in acatalytically effective amount, which amount will generally range fromabout 50 to 5,000 ppm by weight of the monomer feed, preferably 50 to500 ppm (e.g., 70 to 200 ppm) by weight of the monomer feed when themonomer feed comprises >5 wt. % isobutylene, and preferably from about100-5,000 ppm (e.g., 400-3,000 ppm) by weight when the feed comprisesn-butenes and <5 wt. % isobutylene. If anhydrous HCl is added to thefeedstream containing isobutene, t-butyl chloride is formed beforecontact with the solid catalyst.

The order of contacting the monomer feedstream, catalyst, cocatalyst (ifany), and solvent is not critical to this invention. Accordingly, thecatalyst and cocatalyst can be added to the reactor before or afteradding the monomer feedstream and solvent. Alternatively, the catalystand monomer feedstream can be added before or after adding thecocatalyst and solvent.

The degree of polymerization of polymers (and oligomers) produced withthe catalyst of this invention will be determined by the desired enduse. Typically the degree of polymerization is from about 5 to 5,000;more typically from about 10 to about 1,000; for low molecular weightpolymers and oligomers the degree of polymerization will typically beabout 5 to about 100. Correspondingly, the number average molecularweight, M_(n), of a polymeric product will be determined by the monomerand degree of polymerization; for a C₄ -based polymer, typical valuesare from about 300 to about 300,000 gm/mole, depending on the intendedend use of the product. The range of number average molecular weight oflower molecular weight polymeric products will be from about 300 toabout 16,000; more typically about 600 to about 6000 gm/mole. Numberaverage molecular weight is conveniently measured by a suitablycalibrated gel permeation chromatography (GPC) instrument. Thepolydispersity (PDI), also known as the molecular weight distribution(M_(w) /M_(n)) will typically range from about 4 to about 25, moretypically about 5 to about 22, and preferably about 6 to about 20.Unexpectedly, in some instances, a characteristic of the presentcatalyst system is that, during the couse of the polymerization, itproduces two polymers, one being a low molecular weight polymer (Mn onthe order of about 500) with a very narrow molecular weightdistribution, and the other being a higher molecular weight (Mntypically on the order of about 2500 to about 6000) with a much broadermolecular weight distribution.

Lewis acid catalysts of the present invention also find use in otherhydrocarbon conversion processes including alkylation, isomerization andcracking. For example, the catalysts may be employed in the cracking oflong chain hydrocarbons, e.g., heptane, butane, etc., to produce shorterchain products such as ethane, propane, butanes, etc. Additionally, thecatalysts may be used to catalyze the isomerization of normal alkanes totheir branched chain isomers.

The alkylation process of the present invention will be conducted bycontacting the aromatic or hydroxy aromatic substrate and alkylatingagent under reaction conditions, including mole ratio, temperature, timeand catalyst ratio sufficient to alkylate the substrate.

The hydroxy aromatic substrate compounds useful in the preparation ofthe alkylated materials of this invention include those compounds havingthe formula:

    AR--(OH).sub.z

wherein Ar represents ##STR5## and z is an integer from 1 to 2, w is aninteger from 1-3, a is 1 or 2 and R⁴ is a C₁ -C₂₄ alkyl radical.

Illustrative of such Ar groups are phenylene, biphenylene, naphthaleneand the like.

The aromatic substrate compounds useful in the preparation of thealkylated materials of this invention include those compounds having theformulas:

    Ar.sup.1 --R.sup.5.sub.b and (Ar.sup.1 --R.sup.5.sub.b).sub.y

wherein Ar¹ represents: ##STR6## wherein b is one or two; R⁵ is C₁ -C₂₄alkyl, C₃ -C₂₄ cycloalkyl, C₆ -C₁₈ aryl, C₇ -C₃₀ alkylaryl, OH, or H;and y is 1-3.

Illustrative of such Ar¹ groups are benzene, phenylene, biphenylene,naphthalene, and anthracene.

The substrate generally will be contacted in a molar ratio of from about0.1 to 10 preferably from about 1 to 7, more preferably from about 2 to5, moles of the substrate per mole of the alkylating agent. Conventionalratios of alkylating agent typically will be used. The ratio typicallywill be about 0.5 to 2:1, more typically about 0.8 to about 1.5:1, andpreferably about 0.9 to about 1.2:1. The selected catalyst can beemployed in widely varying concentrations. Generally, the catalyst willbe charged to provide at least about 0.001, preferably from about 0.01to 0.5, more preferably from about 0.1 to 0.3, moles of Lewis acidcatalyst per mole of substrate charged to the alkylation reaction zone.Use of greater than 1 mole of the Lewis acid catalyst per mole ofsubstrate is not generally required. The reactants can be contacted withthe present immobilized Lewis acid catalyst system employing anyconventional solid-liquid contacting techniques, such as by passing thereactants through a fixed bed of catalyst particles. The upper limit onthe moles of catalyst employed per mole of substrate compound is notcritical.

The temperature for alkylation can also vary widely, and will typicallyrange from about 10° to 250° C., preferably from about 20° to 150° C.,more preferably from about 25° to 80° C.

The alkylation reaction time can vary and will generally be from about 1to 5 hours, although longer or shorter times can also be employed. Thealkylation process can be practiced in a batchwise, continuous orsemicontinuous manner.

Alkylation processes of the above types are known and are described, forexample, in U.S. Pat. Nos. 3,539,633 and 3,649,229, the disclosures ofwhich are hereby incorporated by reference.

The invention will be understood more fully in conjunction with thefollowing examples which are merely illustrative of the principles andpractice thereof. The invention is not intended to be limited by theseillustrative examples. Parts and percentages where used are parts andpercentages by weight, unless specifically noted otherwise.

EXAMPLE 1

Catalyst Synthesis (SiO₂ /TIBA/MgBu₂ /t-BuCl catalyst)

Silica (W. R. Grace 1952) having a specific area of 300 m² /g wasdehydrated by heating under vacuum at 450° C. for one hour. To 2.6 g ofthe dehydrated silica, there was added 0.9 mmol of triisobutyl aluminum(TIBA) in heptane. After one hour, 3 mmol of MgBu₂ (dibutyl magnesium)was added and the mixture was heated 20 minutes at 80° C. After washingthe resulting solids three times with heptane, 2 ml of puretertiary-butyl chloride (t-BuCl) was added and the silica was againwashed several times with heptane. The silica-supported catalyst system,which was yellow in color, turned orange after drying under vacuum for1.5 hours at 100° C. The resulting dried catalyst system was analyzedand found to contain 1.47% Mg, 0.73% Al and 6.35% Cl.

EXAMPLE 2

Isobutene Polymerization (Runs 1-3)

In a glass flask equipped with a dropping funnel, a thermometer and apressure transducer, there were placed 100 ml of heptane and the amountof isobutene monomer indicated in Table 1. To this mixture, maintainedat -20° C., there was added an amount of the catalyst system prepared inExample 1 containing the indicated amount of aluminum. The contents ofthe flask were maintained at -20° C. for 40 minutes, after which thepolymerization reaction was discontinued and the reaction products wereanalyzed by gel phase chromatography (GPC) in tetrahydrofuran (THF)using polystyrene as the standard. The results are set forth in Table 1hereinbelow. The above procedure was repeated (Runs 2 and 3), exceptthat the polymerization medium was first dried using NaH as a dessicant(Runs 2 and 3), the amounts of monomer (Runs 2 and 3) and catalyst (Run3) were varied, as was the polymerization time (Run 2). Also, thetemperature was permitted to vary over the course of the polymerization(Run 2). In the runs wherein NaH was used as a dessicant, about 0.1 to0.5 g of NaH were introduced under an argon atmosphere from a Schlencktube into the polymerization flask containing about 70 g of the heptanesolvent medium. The monomer was then added to the flask and the mixturewas allowed to stand for about 15 minutes before starting thepolymerization. The results of Runs 2 and 3 are also set forth in Table1.

                  TABLE 1                                                         ______________________________________                                             Mono-                                                                    Run  mer     aluminum T,       Conv.,                                                                              Time                                     No.  moles/l mmoles/l °C.                                                                         ΔT                                                                          %     min. M.sub.n                                                                            M.sub.w                        ______________________________________                                         1*  2.5     0.35     -20   0  56    40   2900 57160                          2    2.8     0.35     -20  21  44    10   2850 29100                          3    3.2     0.2      -20   0  51.5  40   2580 34500                          ______________________________________                                         *without NaH desiccant                                                   

It will be seen from the data in Table 1, that Run 2 (using NaHdesiccant) resulted in a faster rate of conversion.

EXAMPLE 3

Catalyst Synthesis (SiO₂ /MgBu₂ /DEAC/t-BuCl Catalyst)

To 1.4 g of dehydrated silica (W. R. Grace 1952) in 50 ml of heptane,there was added 2.2 mmol of MgBu₂. After 2 hours at room temperature,the silica was washed and 3.7 mmol of diethyl aluminum chloride (DEAC)in heptane were added. After 2 hours, the silica was washed with heptaneand 3 mmol of t-BuCl in heptane were added. After about 1 hour, thesilica was washed and dried under a vacuum for 1.5 hours at 100° C.

EXAMPLE 4

Isobutene Polymerization (Runs 4-5).

The procedure of Example 2 was repeated, except the supported Lewis acidcatalyst system prepared in Example 3 was employed in place of thecatalyst system of Example 1. The polymerization procedure was runtwice, once after using NaH as a desiccant to dry the solvent medium(Run 4) and once without dessicating the solvent medium (Run 5). Theresults of Runs 4 and 5 are set forth below in Table 2.

                  TABLE 2                                                         ______________________________________                                        Run  Monomer  catalyst                                                                              T,    Conv.,                                                                              Time                                        No.  moles/l  g/l     °C.                                                                          %     min. M.sub.n                                                                             M.sub.w                          ______________________________________                                        4*   2.3      0.45    -20   47.6  60   5580   72960                           5    2.6      0.3     -20   37.9  20   7550  101200                           ______________________________________                                         *without NaH desiccant                                                   

The data in Table 2 confirms the increased rate of conversionexperienced when the polymerization is conducted in the presence of theNaH desiccant. The effect on the rate of conversion is relatively high,whereas the effect on the molecular weight is not as high.

EXAMPLE 5

Catalyst Synthesis (SiO₂ /MgBu₂ /AlCl₃ Catalyst

To 2.1 g of dehydrated silica (W. R. Grace 1952) in 60 ml of heptanethere was added 2 ml of a 1 molar solution MgBu₂ in hexane. After onehour, a solution of 0.7 g of AlCl₃ in toluene were added. After heatingfor two hours at 80° C., the silica was washed several times withtoluene. After drying under vacuum at 100° C. for one hour, the catalystsystem was recovered as a green yellow powder. The catalyst was analyzedfor 13.7% Cl, 3.9% Al and 1.2% Mg.

EXAMPLE 6

Isobutene Polymerization (Runs 6-9)

The procedure of Example 2 was repeated, except that the supported Lewisacid catalyst system prepared in accordance with Example 5 was used inplace of the catalyst system of Example 1. The results of this exampleare set forth in Table 3.

                  TABLE 3                                                         ______________________________________                                        Run  Monomer  catalyst                                                                              T,   Conv.,                                                                              Time                                         No.  moles/l  g/l     °C.                                                                         %     min.  M.sub.n                                                                             M.sub.w                          ______________________________________                                        6*   2.17     0.45    -20  36.4  30     9800  79870                           7.sup.1                                                                            2.54     0.36    -20  37.4  30    12280 117140                           8.sup.2                                                                            2.8      0.38    -20  61.3  30    15390 105560                           9*   2.7      0.5     -40  25    60     6300  38000                           ______________________________________                                         *without NaH desiccant                                                        .sup.1 heptaneisobutene mixture maintained over NaH for 0.5 hours             .sup.2 heptaneisobutene mixture maintained over NaH for 2 hours          

EXAMPLE 7

Hexene-1 Oligomerization

To a glass flask, there was added 90 g of the catalyst system preparedin accordance with the procedure of Example 5 (in 50 ml of heptane).Thereafter, 1.4 ml of t-BuCl and 10 ml of hexene were added withstirring. The mixture was stirred for 70 min at room temperature and thereaction was then stopped by filtration of the resulting suspension. Theresulting solution was uncolored and no trace of silica could be seen.After evaporation of the solvent, 2.9 g of product was recovered,corresponding to about a 45% conversion to hexene-1 oligomer.

EXAMPLE 8

Toluene Alkylation

To a glass flask, there was added 272 mg of the catalyst system preparedin accordance with Example 5 (in 100 ml of toluene). There was thenadded 2 ml of tetrapropylene having one unsaturated bond per molecule.After stirring for 1/4 hour at room temperature, the reaction wasstopped by filtration of the resulting suspension. The conversion oftetrapropylene was calculated to be 95% by gas chromatography.

What is claimed is:
 1. A process for cationically polymerizing olefinmonomers, which comprises: contacting olefin monomer under cationicpolymerization reaction conditions with a catalytically effective amountof a supported Lewis acid catalyst that is free from added titanium-,vanadium-, hafnium- and zirconium-containing Lewis acids which comprisesan inorganic oxide substrate having immobilized thereon a catalyticallyeffective amount of at least one strong Lewis acid selected from thegroup consisting of the halides, alkyl halides and alkyl compound ofaluminum and the halides of boron and at least one weak Lewis acidselected from the group consisting of the halides, alkyl halides andalkyl compounds of magnesium, iron, tin and zinc and wherein the molarratio of strong Lewis acid to weak Lewis acid is in the range of fromabout 100:1 to about 1:100.
 2. The process according to claim 1, whereinsaid inorganic oxide substrate comprises a silica component.
 3. Aprocess for alkylating an aromatic or hydroxy aromatic substrate, whichcomprises contacting the substrate with an alkylating agent underalkylation conditions with a catalytically effective amount of asupported Lewis acid catalyst that is free from added titanium-,vanadium-, hafnium- and zirconium-containing Lewis acids which comprisesan inorganic oxide substrate having immobilized thereon a catalyticallyeffective amount of at least one strong Lewis acid selected from thegroup consisting of the halides, alkyl halides and alkyl compound ofaluminum and the halides of boron and at least one weak Lewis acidselected from the group consisting of the halides, alkyl halides andalkyl compounds of magnesium, iron, tin and zinc and wherein the molarratio of strong Lewis acid to weak Lewis acid is in the range of fromabout 100:1 to about 1:100.
 4. In a hydrocarbon conversion processwherein at least one hydrocarbon is contacted with a conversioncatalyst, the improvement comprising contacting said hydrocarbon with asupported Lewis acid catalyst that is free from added titanium-,vanadium-, hafnium- and zirconium-containing Lewis acids and iseffective for catalyzing hydrocarbon conversion reactions, whichcomprises an inorganic oxide substrate having immobilized thereon acatalytically effective amount of at least one strong Lewis acidselected from the group consisting of the halides, alkyl halides andalkyl compound of aluminum and the halides, of boron and at least oneweak Lewis acid selected from the group consisting of the halides, alkylhalides and alkyl compounds of magnesium, iron, tin and zinc and whereinthe molar ratio of strong Lewis acid to weak Lewis acid is in the rangeof from about 100:1 to about 1:100.
 5. The process of claim 4 whereinsaid hydrocarbon conversion is isomerization.
 6. The process of claim 4wherein said hydrocarbon conversion is cracking.